Leishmania donovani

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Leishmania donovani
By Kamran Ahmed

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Introduction

• 1900 Sir William Leishman discovered L.
  donovani in spleen smears of a soldier who died
  of fever at Dum-Dum, India. The disease was known
  locally as Dum-Dum fever or kala-azar.
• 1903 Charles Donovan found same parasite in a
  spleen biopsy.

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Morphology and Life Cycle

• Amastigotes measure 2-3 micrometers, with a large
  nucleus and kinetoplast.
• Amastigotes mainly live within cells of the RE
  system, but have been found in nearly every
  tissue and fluid of the body.

Amastigotes in bone marrow.
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Reticuloendothelial System

• The RES is part of the immune system consisting
  of the phagocytic cells which accumulate in the
  lymph nodes and spleen, the Kupffer cells of the
  liver, and tissue histiocytes.
• Also known as mononuclear phagocytic system or
  lymphoreticular system.

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RES Continued

• Primary lymphoid organs The sites where the RES
  cells are produced. The cells of the RES are
  produced in the bone marrow.
• Secondary lymphoid organs Sites where the RES
  cells function. These sites include the spleen,
  liver, lymph nodes, and intestine.

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Morphology and Life Cycle Continued

• L. donovani is primarily a visceral infection.
• Vector Sand fly of genus Phlebotomus.
• Not all strains of L. donovani are adapted to all
  species and strains of Phlebotomus.

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Pathogenesis

• Infections range from asymptomatic to
  progressive, fully developed kala-azar.
• Incubation period is usually 2 4 months.
• Symptoms Begins with low-grade fever and
  malaise, followed by progressive wasting, anemia,
  and protrusion of the abdomen from enlarged liver
  and spleen.
• Fatal after 2 3 years if not treated.
• In acute cases with chills, fevers up to 104
  degrees Fahrenheit, and vomiting death may occur
  within 6 12 months.
• Immediate cause of death is usually an invasion
  of a secondary pathogen that the body is unable
  to combat.

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Hepatosplenomegaly and emaciation.
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Global Distribution

• 100,000 500,000 cases occur annually.
• Difficult to determine because accurate public
  health records are not kept in some of these
  areas. Also, Leishmaniasis-infected areas overlap
  with HIV-infected areas, and about a third of
  those patients die during their first visceral
  leishmaniasis episode.

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Diagnosis and Treatment

• Tests examine tissues or serums for L-D bodies.
• Most frequently used test is the enzyme-linked
  immunosorbent assay (ELISA).
• ELISA Multi-step process of detecting if a
  person is infected by analyzing antibody-antibody
  interactions of the patients serum.
• Miltefosine has cured up to 98 of VL cases.
• Control of the disease is based on control of the
  sand fly population.